The Unreal Engine is a game engine developed by Epic Games, first showcased in the 1998 first-person shootergameUnreal. Although primarily developed for first-person shooters, it has been successfully used in a variety of other genres, including stealth, MMORPGs, and other RPGs. With its code written in C++, the Unreal Engine features a high degree of portability and is a tool used by many game developers today.[3]

Making its debut in 1998 with Unreal, the first generation Unreal Engine integrated rendering, collision detection, AI, visibility, networking, scripting, and file system management into one complete engine. Unreal Engine 1 provided an advanced software rasterizer[11] and a hardware-accelerated rendering path using the Glide API, specifically developed for 3dfx GPUs,[12] and was updated for OpenGL and Direct3D. Large parts of the game were implemented in a custom scripting language called UnrealScript. The initial network performance was also very poor when compared to its biggest competitor, Quake II. Epic used this engine for both Unreal and Unreal Tournament. The release of Unreal Tournament marked great strides in both network performance and Direct3D and OpenGL support.[13]

The second version made its debut in 2002 with America's Army, a free multiplayer shooter created and funded by the US Army. This generation saw the core code and rendering engine completely re-written. In addition, it featured UnrealEd 2, which debuted with the previous generation of the engine and was shortly followed later by UnrealEd 3, along with the Karma physics SDK. This physics engine powered the ragdoll physics in Unreal Tournament 2003 and Unreal Championship. Other engine elements were also updated, with improved assets as well as adding support for the GameCube and the Xbox. Support for the PlayStation 2 console was previously added in UE1. Taking Xbox aside, both GameCube and PS2 were never supported directly by Epic, support being instead farmed out to Secret Level said builds were stale and left behind, the last "official" build PS2 and GC saw was build 927 dated April 2002; last official UE2.5 build was build 3369. As such, third parties looking to use further Unreal Engine revisions had to do their own builds throughout the generation, as they had to in more recent years with the Wii, X360, PS3, PSP, and 3DS.[citation needed]

UE2.5, an update to the original version of UE2, improved rendering performance and added vehicles physics, a particle system editor for UnrealEd, and 64-bit support in Unreal Tournament 2004. A specialized version of UE2.5 called UE2X was used for Unreal Championship 2: The Liandri Conflict on the original Xbox platform. It featured optimizations specific to that console. EAX 3.0 is also supported for sound. Unreal Engine 2.X was build 2227, dated March 2004.

The first screenshots of Unreal Engine 3 were presented in 2004,[27] at which point the engine was in development for 18 months already.[28] Unlike Unreal Engine 2, which still supported fixed-function pipeline, Unreal Engine 3 was designed to take advantage of fully programmable shader hardware (in DirectX 9 terms, it required shader model 3.0). All lighting calculations were done per-pixel, instead of per-vertex. On the rendering side, Unreal Engine 3 also provided support for a gamma-correct high-dynamic range renderer. UE3 expected that content was authored in both high- and low-resolution version and baked normal maps for run-time; a major difference to previous generations where the game content was modeled directly (since normal mapping is a per-pixel operation and almost all the dynamic lighting in UE1 and 2 was calculated per-vertex using a Gouraud Shading technique)

The third generation of the Unreal Engine is designed for DirectX (versions 9-11 for Windows, Windows RT and Xbox 360), as well as systems using OpenGL, including the PlayStation 3, OS X, iOS, Android, Stage 3D for Adobe Flash Player 11, JavaScript/WebGL for HTML5Web Browsers,[29]PlayStation Vita, and Wii U.[30] Initially, Unreal Engine 3 only supported Windows, Xbox 360, and PlayStation 3 platforms, while Android and iOS were added later in 2010 (with Infinity Blade being the first iOS title and Dungeon Defenders the first Android title). OS X support was added in 2011.[31] Its renderer supports many advanced techniques including HDRR, per-pixel lighting, and dynamic shadows. It also builds on the tools available in previous versions. In October 2011, the engine was ported to support Adobe Flash Player 11 through the Stage 3D hardware-accelerated APIs. Epic has used this version of the engine for their in-house games. Aggressive licensing of this iteration has garnered a great deal of support from many prominent licensees. Epic has announced that Unreal Engine 3 runs on both Windows 8 and Windows RT.[32] The first released console game using Unreal Engine 3 was Gears of War and the first released PC game was RoboBlitz.

Throughout the lifetime of the UE3, significant updates have been incorporated:

In December 2009, Epic demoed UE3 running on Apple's 3rd generation iPod Touch. They said that this will also support iPhone 3GS, and also an unknown mobile platform which has been revealed to be webOS at CES 2010.[34] It has been revealed so far to be something on Nvidia's Tegra platform, and also Palm's webOS running PowerVR's SGX chip.

In March 2010, Steamworks was integrated into the software, and is offered to licensees.[35]

As of March 2011, the Unreal 3 Engine supports DirectX 11. Epic Games showcased it with a real-time demonstration video, entitled "Samaritan".[39] Additions include tessellation and displacement mapping, advanced hair rendering with MSAA, deferred shading with MSAA, screen space subsurface scattering, image-based lighting, billboard reflections, glossy reflections, reflection shadows, point light reflections, and bokehdepth of field.[40] The Samaritan demo was unveiled during GDC 2011 as a proof of concept and target for the "3.5" version of Epic's Unreal Engine 3, ostensibly aimed at next-generation platforms.[41][42] It was built by Epic Games in a close partnership with NVIDIA, with engineers working around to country to push real-time graphics to a new high point.[43]

While Unreal Engine 3 has been quite open for modders to work with, the ability to publish and sell games made using UE3 was restricted to licensees of the engine. However, in November 2009, Epic released a free version of UE3's SDK, called the Unreal Development Kit (UDK), that is available to the general public.[53] According to the current EULA, game developers can sell their games by paying Epic the cost of $99 USD, and 25% royalty on UDK related revenue above US$50,000 from all UDK-based games or commercial applications.[54][55]

The December 2010 UDK release added support for creating iOS games and apps. UDK's iOS development feature set includes:[56][57]

The full source and content for Epic Citadel, plus an additional castle demo map.

Support for major Unreal Engine 3 desktop features, including the Unreal Editor and its fully integrated suite of tools including Unreal Kismet, Unreal Cascade and Unreal Matinee.

On August 17, 2005, Mark Rein, the vice-president of Epic Games, revealed that Unreal Engine 4 had been in development since 2003.[69] Until mid-2008, development was exclusively done by Tim Sweeney, founder and technical director of Epic Games.[70] The engine targets the eighth generation of consoles, PCs and Tegra K1-based[71] devices running Android announced in January 2014 at CES.

In February 2012, Mark Rein said "people are going to be shocked later this year when they see Unreal Engine 4".[72] Unreal Engine 4 was unveiled to limited attendees at the 2012 Game Developers Conference,[73] and video of the engine being demonstrated by technical artist Alan "Talisman" Willard was released to the public on June 7, 2012 via GameTrailers TV.[74][75] This demo was created on a PC with triple GeForceGTX 580 (tri SLI) and can be run on a PC with a GeForceGTX 680.[76]

One of the major features planned for UE4 was real-time global illumination using voxel cone tracing, eliminating pre-computed lighting.[77] However, this feature has been replaced with a similar but less computationally-expensive algorithm prior to release for all platforms including the PC because of performance concerns on next-generation consoles.[78] UE4 also includes new developer features to reduce iteration time, and allows updating of C++ code while the engine is running. The new "Blueprint" visual scripting system (a successor to UE3's "Kismet"[79]) allows for rapid development of game logic without using C++, and includes live debugging.[80][81] The result is reduced iteration time, and less of a divide between technical artists, designers, and programmers.[82]

“

[In older engines], if you wanted to change the relationship between your weapon damage and how long it'll take to kill a creature, you may spend a couple of days iterating, but if you have to spend a lot of time waiting for a build every time, you're talking one change, waiting 15 minutes for the compile to complete, and then play the game, get to the point where you can test it, test it, exit the game, change, compile... Now, since all of that can be done very quickly within the tools, it's 'Make the change, play, when it compiles, finish, shoot the guy, and then escape, make the change, play'. The iteration time is down to 30 seconds instead of 15 minutes. Our ability to kind of roll through and see how the game is playing out is much faster.

On March 19, 2014, at the 2014 Game Developers Conference, Epic Games opened Unreal Engine 4 to the world, releasing all of its leading-edge tools, features and complete C++ source code to the development community through a new subscription model. Anyone can sign up for UE4 for PC, Mac, iOS and Android by paying $19 per month, plus 5% of gross revenue resulting from any commercial products built using UE4.[83][84] CEO and founder of Epic Games, Tim Sweeney, said that the new business model is a reflection of changes in the industry. Epic Games has traditionally made its Unreal Engine available to large AAA game development teams at a cost of millions of dollars but as the industry has evolved, Epic has had to "really rethink our whole business as to how we make the engine available to teams."[85][86] "Looking at the new shape of the industry now, we realize that's an outdated tool," Sweeney said. "Looking at the possibilities for the engine, we started from scratch and thought 'How can we make the engine available to more people?'".[87] According to the Unreal Engine website, subscribers to the engine will be able to cancel their subscription, or renew it at any time. They will be able to retain access to UE4 tools, but will not receive access to future releases of Unreal Engine 4.[88]

On September 3, 2014, Epic Games launched the Unreal Engine Marketplace, allowing UE4 subscribers to buy and sell community-created content of all shapes and sizes.[89] In addition to all of the previously released free content, the new marketplace was launched with a variety of asset packs including full-scale environments, props, characters, sounds, materials, animated meshes, prefab C++ code and a number of other asset types as well as free demos and tutorials.[90][91]

On September 4, 2014, Epic released Unreal Engine 4 to schools and universities for free, including personal copies for students enrolled in accredited video game development, computer science, art, architecture, simulation, and visualization programs.[92][93] "Nothing is stopping students from honing the skills needed to enter the range of fields using Unreal Engine technology, from entertainment software and film to visualization, healthcare simulation and military training," Unreal Engine general manager Ray Davis said in a statement. "Students who know Unreal Engine technology have a huge advantage when it comes to job placement."[94] Schools can integrate the same fully featured version of Unreal Engine 4 previously available only to developers, along with all future updates.[95] In addition, students retain indefinite access to any versions of the engine used during their coursework which gives them the option to turn their class projects into shipping projects at any time.[96]

On March 2, 2015, Epic announced that “Unreal Engine 4 is now available to everyone for free, and all future updates will be free!" [97] The same post specifies that a 5% royalty in gross must be paid after the first $3,000USD per product, per quarter.

^"History of Unreal - Part 1". beyondunreal.com. 2005-05-31. Retrieved 2009-07-05. Probably the biggest draw to Unreal was the ability to mod it. Tim Sweeney (Founder of Epic) wrote a simple scripting engine into the game called UnrealScript.